>|hyidZddlZddlmZddlmZGddeZGdd eZeZ dd Z Gd d Z Gd dZ y)a SteadyDB - hardened DB-API 2 connections. Implements steady connections to a database based on an arbitrary DB-API 2 compliant database interface module. The connections are transparently reopened when they are closed or the database connection has been lost or when they are used more often than an optional usage limit. Database cursors are transparently reopened as well when the execution of a database operation cannot be performed due to a lost connection. Only if the connection is lost after the execution, when rows are already fetched from the database, this will give an error and the cursor will not be reopened automatically, because there is no reliable way to recover the state of the cursor in such a situation. Connections which have been marked as being in a transaction with a begin() call will not be silently replaced either. A typical situation where database connections are lost is when the database server or an intervening firewall is shutdown and restarted for maintenance reasons. In such a case, all database connections would become unusable, even though the database service may be already available again. The "hardened" connections provided by this module will make the database connections immediately available again. This approach results in a steady database connection that can be used by PooledDB or PersistentDB to create pooled or persistent connections to a database in a threaded environment such as the application server of "Webware for Python." Note, however, that the connections themselves may not be thread-safe (depending on the used DB-API module). For the Python DB-API 2 specification, see: https://www.python.org/dev/peps/pep-0249/ For information on Webware for Python, see: https://webwareforpython.github.io/w4py/ Usage: You can use the connection constructor connect() in the same way as you would use the connection constructor of a DB-API 2 module if you specify the DB-API 2 module to be used as the first parameter, or alternatively you can specify an arbitrary constructor function returning new DB-API 2 compliant connection objects as the first parameter. Passing just a function allows implementing failover mechanisms and load balancing strategies. You may also specify a usage limit as the second parameter (set it to None if you prefer unlimited usage), an optional list of commands that may serve to prepare the session as a third parameter, the exception classes for which the failover mechanism shall be applied, and you can specify whether is is allowed to close the connection (by default this is true). When the connection to the database is lost or has been used too often, it will be transparently reset in most situations, without further notice. import pgdb # import used DB-API 2 module from dbutils.steady_db import connect db = connect(pgdb, 10000, ["set datestyle to german"], host=..., database=..., user=..., ...) ... cursor = db.cursor() ... cursor.execute('select ...') result = cursor.fetchall() ... cursor.close() ... db.close() Ideas for improvement: * Alternatively to the maximum number of uses, implement a maximum time to live for connections. * Optionally log usage and loss of connection. Copyright, credits and license: * Contributed as supplement for Webware for Python and PyGreSQL by Christoph Zwerschke in September 2005 * Allowing creator functions as first parameter as in SQLAlchemy suggested by Ezio Vernacotola in December 2006 Licensed under the MIT license. N)suppress) __version__ceZdZdZy) SteadyDBErrorzGeneral SteadyDB error.N__name__ __module__ __qualname____doc__P/var/www/html/test/engine/venv/lib/python3.12/site-packages/dbutils/steady_db.pyrrbs!rrceZdZdZy)InvalidCursorErrorzDatabase cursor is invalid.Nrr rrrrfs%rrc*t||||||g|i|S)aCreate a "tough" connection. A hardened version of the connection function of a DB-API 2 module. creator: either an arbitrary function returning new DB-API 2 compliant connection objects or a DB-API 2 compliant database module maxusage: maximum usage limit for the underlying DB-API 2 connection (number of database operations, 0 or None means unlimited usage) callproc(), execute() and executemany() count as one operation. When the limit is reached, the connection is automatically reset. setsession: an optional list of SQL commands that may serve to prepare the session, e.g. ["set datestyle to german", "set time zone mez"] failures: an optional exception class or a tuple of exception classes for which the failover mechanism shall be applied, if the default (OperationalError, InternalError, Interface) is not adequate for the used database module ping: determines when the connection should be checked with ping() (0 = None = never, 1 = default = when _ping_check() is called, 2 = whenever a cursor is created, 4 = when a query is executed, 7 = always, and all other bit combinations of these values) closeable: if this is set to false, then closing the connection will be silently ignored, but by default the connection can be closed args, kwargs: the parameters that shall be passed to the creator function or the connection constructor of the DB-API 2 module )SteadyDBConnection)creatormaxusage setsessionfailuresping closeableargskwargss rconnectrns/8 :$  4$( 4,2 44rceZdZdZeZ ddZdZdZdZ ddZ dZ d Z dd Z dd Zd Zd ZdZdZdZdZdZdZdZdZdZy)rz+A hardened version of DB-API 2 connections.Nc>d|_d|_ |j|_ |jjr|j|_ |j|_ t|jst|d|d}t|t s td||_||_|+t|t&st)|t*s td||_t|t r|nd|_||_||c|_|_|j7|j9y#t $r ||_YwxYw#t $r||_ |j|_nn#t $rb tj|j|_|j j|k7rt n#t tf$r d|_YnwxYwYnwxYwYwxYw#t $r7 |j j|_ n#t $r d|_ YnwxYwYwxYw)z%Create a "tough" DB-API 2 connection.NTz is not a connection provider.rz$'maxusage' must be an integer value.z)'failures' must be a tuple of exceptions.)_con_closedr_creatordbapi_dbapiAttributeErrorsysmodulesr KeyError threadsafety _threadsafetycallable TypeError isinstanceint _maxusage_setsession_sqltuple issubclass Exception _failures_ping _closeable_args_kwargs_store_create) selfrrrrrrrrs r__init__zSteadyDBConnection.__init__s    '#OODM &==((")--DK *!(!5!5D   &wk)GHI I  H(C(BC C!)   %)!)3Hi)HGH H!'c2T ##'  DL DLLN#I" &%  & '#DM '%mm ! ''"%++g.@.@"ADK{{**g5,,6&1'"&DK'  ' ' * *%)[[%=%="! *%)" * *sE'D. G.E>EEEGE'&G' G1AF32G3G  G G  GGGGG H&HHHHHHHc|S)z4Enter the runtime context for the connection object.r r:s r __enter__zSteadyDBConnection.__enter__ rcd|d|d|d|jy|jy)zExit the runtime context for the connection object. This does not close the connection, but it ends a transaction. rNr)commitrollbackr:excs r__exit__zSteadyDBConnection.__exit__s/ q6>c!fnQ KKM MMOrcV|j|ji|j} |jj|jk7rt  |j |jj|_ |j G |jj|jj"|jj$f|_t'|j t(r|j d|_n|j |_|j-||S#t $rA |j }n#t $rd}YnwxYw|ru tj||_t|jjst  n#t tf$rYnwxYw|jd}|dkrdn|d|}|ru |jj }n#t $rd}YnwxYw|ru tj||_t|jjst  n<#t tf$rYnwxYw|jd}|dkrdn|d|}|rud|_YwxYw#t $r:tt 5|j|_ dddn #1swYnxYwY6wxYw#t $r |jj|jj"|jj$f|_nV#t $rJ |j|j"|j$f|_n#t $r}t d|d}~wwxYwYnwxYwYwxYw#t.$r<}tt.5|j1ddd|#1swY|xYwd}~wwxYw)z3Create a new connection using the creator function.N.rzNCould not determine failure exceptions (please set failures or creator.dbapi).)r!r6r7r#rr$r r%r&r*r'rfindOperationalErrorr)r(rr3InterfaceError InternalErrorr,r0_failure _setsessionr2close)r:conmodierrors rr9zSteadyDBConnection._createswdmmTZZ84<<8N % +;;&&$--7((8J!!)>)-)A)AD&~~%) 44 22 11&3DN*$..%0 $q 1 $   S ! W"" +..C%C&)kk#&6 ' (;(;<"00 = +H5 #A"#a%$S!WC#!22==)#"#"*-++c*:DK#+DKK,?,?#@&4 4$A "!/9! ! IIcN&'!edRa'+ E" +L&>!.1>-0-=-=*>>>>&)) MM:: MM88 MM77*9* ) ) # 4 4 # 2 2 # 1 1.3DN .)"0!K#$))) + ) ), )$   K K  s)D! M# I/; M#AJ5AM#! I,, D98I,9 EI,EI, =F  I, FI,F"I,GI, G'$I,&G''I,-=H,+I,,H>;I,=H>>"I,!I,(M#+I,,M#/J2J" J2"J+ 'J2.M#1J22M#5 M ?ALM  M(L98M9 M MMMM MM M#M  M## N(,N#;N N#N N##N(c| |j}|jrC|j}|jD]}|j||j yy)z1Execute the SQL commands for session preparation.N)rr/cursorexecuterO)r:rPrUsqls rrNzSteadyDBConnection._setsession)sS ;))C   ZZ\F++ $s# $ LLN rc<||_d|_d|_d|_y)z/Store a database connection for subsequent use.FrN)r _transactionr _usage)r:rPs rr8zSteadyDBConnection._store3s !  rc|jsAtt5|jj dddd|_d|_yy#1swYxYw)zClose the tough connection. You can always close a tough connection with this method, and it will not complain if you close it more than once. NFT)r rr2rrOrYr=s r_closezSteadyDBConnection._close:sJ ||)$ " ! " %D DL  " "s AAc|js8|s |jr)tt5|j dddyyy#1swYyxYw)zfReset a tough connection. Rollback if forced or the connection was in a transaction. N)r rYrr2rC)r:forces r_resetzSteadyDBConnection._resetFsG ||$*;*;)$    +<|  s AAc||jzrl |jjd}|d}|rd} |rB|js6 |j}|j|j|d}|S|Sy#t$r|jj}YuwxYw#tt tt f$rd|_d}d}Yt$rd}YwxYw#t$rY|SwxYw)a Check whether the connection is still alive using ping(). If the underlying connection is not active and the ping parameter is set accordingly, the connection will be recreated unless the connection is currently inside a transaction. FNTr) r4rrr+r$ IndexError ValueErrorr2rYr9r\r8)r:r reconnectaliverPs r _ping_checkzSteadyDBConnection._ping_checkOs $**  &- IINN51E= E %I!2!2!,,.CKKMKK$ EL5L/!- IINN,E-"J :F " !   ! L sAA=C=#B# B&"B##B&&$C CC C)(C)cH|j td|jS)z8Return the underlying DB-API 2 module of the connection.z?Could not determine DB-API 2 module (please set creator.dbapi).)r#r$r=s rr"zSteadyDBConnection.dbapiss* ;;  /0 0{{rcb|j|j tdy|jS)z1Return the thread safety level of the connection.zTCould not determine threadsafety (please set creator.dbapi or creator.threadsafety).r)r)r#r$r=s rr(zSteadyDBConnection.threadsafety{s>    %{{"$KLL!!!rcx|jr|jy|jr|jyy)a^Close the tough connection. You are allowed to close a tough connection by default, and it will not complain if you close it more than once. You can disallow closing connections by setting the closeable parameter to something false. In this case, closing tough connections will be silently ignored. N)r5r\rYr_r=s rrOzSteadyDBConnection.closes+ ?? KKM    KKMrcnd|_ |jj}||i|y#t$rYywxYw)aHIndicate the beginning of a transaction. During a transaction, connections won't be transparently replaced, and all errors will be raised to the application. If the underlying driver supports this method, it will be called with the given parameters (e.g. for distributed transactions). TN)rYrbeginr$)r:rrrjs rrjzSteadyDBConnection.beginsA! #IIOOE 4 "6 "   s ( 44cd|_ |jjy#|j$rI} |j }|j |j ||#t$rY|wxYwd}~wwxYw)zCommit any pending transaction.FN)rYrrBr3r9r\r8r2r:rSrPs rrBzSteadyDBConnection.commitsy!  II   ~~  !lln  C K  K   2$A<A'#A7' A40A73A44A77A<cd|_ |jjy#|j$rI} |j }|j |j ||#t$rY|wxYwd}~wwxYw)zRollback pending transaction.FN)rYrrCr3r9r\r8r2rls rrCzSteadyDBConnection.rollbacksy!  II   ~~  !lln  C K  K   rmcld|_ |jj}|y#t$rYywxYw)zvCancel a long-running transaction. If the underlying driver supports this method, it will be called. FN)rYrcancelr$)r:rps rrpzSteadyDBConnection.cancels; " YY%%F H   s ' 33c:|jj|i|S)zPing connection.)rrr:rrs rrzSteadyDBConnection.pingstyy~~t.v..rcn|j}|s|jd |jr'|j|jk\r|s |j|j j |i|}|S#|j$r} |j} |j |i|}|j|j||r||cYd}~S#t$rYnwxYwtt5|jdddn#1swYnxYw#t$rYnwxYw|rd|_|d}~wwxYw)z]Create a "tough" cursor. This is a hardened version of the method cursor(). rANF)rYrer.rZrMrrUr3r9r\r8r2rrO)r:rr transactionrUrSrPs r_cursorzSteadyDBConnection._cursors/''    Q  4;;$..#@'mm#%TYY%%t6v6F, +~~  lln "'SZZ88FKKMKK$"# !M!i( IIK     $)!K) srAA22D4DC%&D/ D4 CD/CD//D  D/ D D/ D!D/ D!!D//D4c t|g|i|S)z0Return a new Cursor Object using the connection.)SteadyDBCursorrrs rrUzSteadyDBConnection.cursorsd4T4V44rc4 |jy#YyxYw)zDelete the steady connection.N)r\r=s r__del__zSteadyDBConnection.__del__s  KKM  NNNrTN)F)rT)r r r r rversionr;r>rFr9rNr8r\r_rer"r(rOrjrBrCrprrurUryr rrrrs{5G6:-11$fRh   "H" #"   /%N5rrc\eZdZdZdZdZdZdZdZddZ d Z dd Z d Z d Z d ZdZy)rwz'A hardened version of DB-API 2 cursors.cd|_d|_||_||c|_|_|j  |j|i||_d|_y#t $r}t|d|d}~wwxYw)z!Create a "tough" DB-API 2 cursor.NTz is not a SteadyDBConnection.F)rur rr6r7 _clearsizesr$r+)r:rPrrrSs rr;zSteadyDBCursor.__init__ s   #'  DL  P&3;;77DL  Psg%BCD% O PsA A2A--A2c|S)z0Enter the runtime context for the cursor object.r r=s rr>zSteadyDBCursor.__enter__r?rc$|jy)z/Exit the runtime context for the cursor object.NrOrDs rrFzSteadyDBCursor.__exit__s  rc||j} t|S#t$rt|jdcYSwxYw)z1Make cursor compatible to the iteration protocol.N)ruiterr+fetchone)r:rUs r__iter__zSteadyDBCursor.__iter__"s: /<  /. . /s ;;c||_y)z6Store input sizes in case cursor needs to be reopened.N) _inputsizes)r:sizess r setinputsizeszSteadyDBCursor.setinputsizes*s  rNc"||j|<y)z7Store output sizes in case cursor needs to be reopened.N) _outputsizes)r:sizecolumns r setoutputsizezSteadyDBCursor.setoutputsize.s$(&!rc g|_i|_y)z$Clear stored input and output sizes.N)rrr=s rrzSteadyDBCursor._clearsizes2src| |j}|jr|j|j|jj D]+\}}||j ||j ||-y)z7Set stored input and output sizes for cursor execution.N)rurrritemsr)r:rUrrs r _setsizeszSteadyDBCursor._setsizes7sr >\\F     !1!1 2 --335 3LFD~$$T*$$T62  3rc|js:tt5|jj dddd|_yy#1swYxYw)z^Close the tough cursor. It will not complain if you close it more than once. NT)r rr2rurOr=s rrOzSteadyDBCursor.closeCsD ||)$ % ""$ %DL % %s AAcfd}|S)z4Return a "tough" version of the given cursor method.c4 jd}j}|j}|s|jd |jr'|j |jk\r|s |j |rjtj }||i|}|rj|xj dz c_|S#|j$r}|s |jjij} |rj|t| }||i|}|rjj|_ |xj dz c_|cYd}~S#t$rYnwxYwt!t5|jdddn#1swYnxYw#t$rYnwxYw |j#} | j$jij}|r:j|j'|j)| |_ |d} |rj|t| } | |i|}|rjd} n.#|j*$rd} |} Ynt$r}d} |} Yd}~nd}~wwxYw| rXj|j'|j)| |_ |xj dz c_| r| cYd}~St!t5|jdddn#1swYnxYw#t$rYnwxYwt!t5| jdddn#1swYnxYw#t$rYnwxYw|rd_d}~wwxYw)NrVrTF) startswithrrYrer.rZrMrgetattrrurr3r6r7rOr2rr9rUr\r8 __class__)rrrVrPrtmethodresultrScursor2con2error2method2use2namer:s r tough_methodz6SteadyDBCursor._get_tough_method..tough_methodOsTooi0G))C**K"V MMcjjCMM&A +,,&NN$ t400$$&V a  W==H ","-#++!ZZ#9+/<<#9 *& $w 7%,Wd%;F%+T%-N+N1 E=:N<E==NF) N)F2 .N5 G>NGNM8&L4<>N;9I74N7J" N J"JNJ""AN9N?NL( N(L1 -N4 M=N?MNM,# N,M5 1N8 NNNNNr )r:rrs`` r_get_tough_methodz SteadyDBCursor._get_tough_methodMs\ zrc|jr8|jdr|j|St|j|St)z4Inherit methods and attributes of underlying cursor.)rVcall)rurrrr)r:rs r __getattr__zSteadyDBCursor.__getattr__s> <<23--d334<<. .  rc4 |jy#YyxYw)zDelete the steady cursor.Nrr=s rryzSteadyDBCursor.__del__s  JJL  rzr|)r r r r r;r>rFrrrrrrOrrryr rrrwrwsC1 /!) 3 _B!rrwr{) r r% contextlibrrr2rr InvalidCursorrrrwr rrrs]Yv "I"&& # ,0)-4Bvvr uur